Won't start - electrical short?

matt497911 · January 17, 2017, 07:14 PM

i have a 1975 winne chieftain.ive been trying to get the thing running but i have a major short somewhere. the fusable link from the starter relay wuz blown so i put a fuse in instead. i have been trying to locate the short i have narrowed it down to befor the ignition switch and its not in the dash. is there any common places where these things short?. also i am looking for the connection where the main wire from the starer relay splits off to give power to everything because that will make life alot easier in locating this short. any ideas???

DRMousseau · January 17, 2017, 08:34 PM

mmmmm,.... before the ignition switch and not in the dash??? I'd be lookin' at the harness connector plug of the ignition switch assy, and other column wiring. BTW,... I have a new, unused replacement turn signal switch assembly for these early Dodge chassis if anyone is in need and interested. Never got installed in the ol' Winnebago.

These "popping" sounds ya hear, are USUALLY from a break in the wiring circuit. Sometimes, a fuse "breaks" or "PoPs",.... sometimes a weak or corroded wire breaks. And other times, a bare short has arched too many times and finally breaks. Wire terminal connectors can also weaken, corrode, or simply "break" and "pop" due to high current draw thru the point of connection.

"Shorts" almost ALWAYS cause a fuse to "blow",... safety feature, ya know? Finding a short and/or verifying the continuity and power presense isn't always easy for most folks,... and even simple diagrams can be confusing. Add weak and/or poor connections, intermittent shorts and maybe some other quirky things,.... well, I usually suggest finding someone with good skills or jus do it myself for folks. Trying to guide others can be pretty tough most times.

DaveVA78Chieftain · January 17, 2017, 10:10 PM

First, you need the chassis wiring diagrams. By becoming a site member ($5) you will have access to the wiring diagrams in the member area. Or purchase the Service Manual. The main line (A20 circuit; 10 gauge black wires) from the relay goes 4 places:
1: Alternator
2: Fuse Block
3: Ignition Switch
4: Headlight Switch

Connectors are near the floor at the base of the Steering wheel

You need those wiring diagrams to isolate the paths.

matt497911 · January 17, 2017, 10:15 PM

i just spent a couple hours looking through things again and have icolated the problem to the altenator. thanks fr the help

M & J · January 17, 2017, 11:06 PM

Still worthwhile to join Matt.

TerryH · January 18, 2017, 01:35 AM

For future reference, the difference between a fuse, fusible link, relay and - very common - poor ground connection are myriad.
There is a highly recommended flow chart to follow when searching for an electrical fault.
Should you need it, just ask.
Dave is an electric guru.

matt497911 · January 19, 2017, 01:34 PM

good to know thank you

DRMousseau · January 20, 2017, 03:27 AM

Oh yes,... I found that small cost of membership to have been ABSOLUTLY INDISPENSABLE with the ol' Winnebago!!!

And the knowledge of these folks here,.... jus plain INVALUABLE!!!!

matt497911 · August 05, 2017, 04:24 PM

ive located a new wiring problem. when i turn on my main breaker the lights will work for like 10 minuts then shut off but is not tripping the breakers so i will turn off the main breaker turn them back on and will work for 5 min repeat that till i have to wait like 10 15 min to restart it and then it starts all over again so i started popin out breakers to locate the curcut and it is the main one (the top one on the row of fuses)any ideas what the problem is?

Rickf1985 · August 05, 2017, 05:58 PM

I would guess you have a loose connection and it is arcing or heating up and eventually open circuits. Once power is removed it cools off and reconnects. This can be very dangerous and can cause a fire. I strongly suggest you disconnect from all power and then go over all of the connections in the power panel. Every single connection!

matt497911 · August 05, 2017, 10:27 PM

so i did some diagnostics and have located the problem to the batteycharger it will start charging the battery for about 15 20 seconds then shut down i dont know if this is common problem and its not like the battery is fully charged or it will charge to a certain voltage than stop.it shuts of with a click coming from an internal switch i the inverter. if need to i will unplug the battery charger and just put my own separate one in is this a common problem or any ideas on how to fix it?

Rickf1985 · August 06, 2017, 09:37 AM

Are you sure you do not have a bad battery? f not then the charging unit may have bite the dust. I thought you were talking about the 110 volt side of things? Is that part all working as it should? So what I am seeing is that you have either totally dead batteries or no batteries and you are running totally on the converter, correct? It sounds to me like what you are hearing is a thermal breaker tripping. An overload on the DC side possibly? Do you have the fridge set for DC?

matt497911 · August 06, 2017, 01:17 PM

i have checked everything else on the 110 circuit and it is infact the transformer because i took the one wire from the breaker and ran power directly from the battery and watched it with a multimeter and it will charge for a small amout of time and trip so i then wanted to make sure the battery wasnt flat so i ran jumpers to my daily driver and the same thing wil happen so is this just a normal cycle or is my transformer done? and is there a way to test these transformers befor i replace it?

matt497911 · August 06, 2017, 01:18 PM

also i did run power to the transformer and not to the battery to see if there in a short in the winding this isnt the case it just trips when i put any sort of load on it

Rickf1985 · August 06, 2017, 06:25 PM

Sounds like it is bad to me but Dave is an expert on these converters and I am sure he will pick up on this later this evening. This is not a normal cycle to lose all DC power to the coach. If the batteries are fully charged, depending on what charger it is then it might stop charging but it should never pop a breaker.

matt497911 · August 06, 2017, 08:26 PM

thanks for the feedback ill see what dave says befor i replace it thank

DaveVA78Chieftain · August 06, 2017, 09:18 PM

Your comments are somewhat confusing. So to start, I need to know the model and part number of the converter and power panel you have. I suspect it is either a PD 743Q of PD 765Q.
When there is no AC power to the rig, the transfer relay de-energizes and the battery supplies 12VDC to the rig via the blue wire on the relay to the DC fuse panel. Does that mode work? If not is the battery dead/shorted. A bad battery will take down the charging circuit and possibly DC power to the rig.
When AC is supplied to the rig, the transfer relay energizes and supplies 12VDC power to the rig via the blue wire on the relay to the DC fuse panel. Converter: AC power to the step down transformer, stepped down AC power to the diodes, DC power from the diodes to the transfer relay. The diodes do have a thermal protection circuit.
Battery charge circuit regulates also uses the diode output however it regulates a charge voltage to the battery.

When the AC is ON, power to the rig is via the blue wire on the transfer relay.
The charge circuit supplies voltage back to the battery separately over the red wire going back to battery. In other words, 2 separate paths.